The state of Atherosclerosis in carotids or other blood vessels can be studied using magnetic resonance imaging (MRI) or Ultrasound imaging. Because ultrasound offers several advantages like real time scanning of blood vessels, compact in size, low cost, easy to transport (portability), easy availability and visualization of the arteries are possible, Atherosclerosis quantification is taking a new dimension using ultrasound. Because one can achieve compound and harmonic imaging, which generates high quality images with ultrasound, it is thus possible to do two-dimensional (2D) and three-dimensional (3D) imaging of blood vessel ultrasound images for monitoring of Atherosclerosis.
In recent years, the possibility has arisen of adopting a composite thickness of the tunica intima and media, an intima-media thickness (hereinafter referred to as an “IMT” or “CIMT”) of carotid arteries, as surrogate marker for cardiovascular risk and stroke. Conventional methods of imaging a carotid artery using an ultrasound system, and measuring the IMT using an ultrasonic image for the purpose of diagnosis are being developed.
A conventional measuring apparatus can measure an intima-media thickness of a blood vessel using an ultrasound device to scan the blood vessel. Then, for example, an image of a section of the blood vessel including sections of the intima, media and adventitia is obtained. The ultrasound device further produces digital image data representing this image, and outputs the digital image data to a data analyzing device.
The intima, media and adventitia can be discriminated on the basis of changes in density of tissue thereof. A change in density of tissue of the blood vessel appears as a change of luminance values in the digital image data. The data analyzing device detects and calculates the intima-media thickness on the basis of the changes of luminance values in the digital image data. The digital image data can include a plurality of luminance values each corresponding to respective one of a plurality of pixels of the image. The data analyzing device can set a base position between a center of the blood vessel and a position in a vicinity of an inner intimal wall of the blood vessel on the image, on the basis of a moving average of the luminance values. The data analyzing device can detect a maximum value and a minimum value from among the luminance values respectively corresponding to a predetermined number of the pixels arranged from the base position toward a position of an outer adventitial wall on the image. The data analyzing device can then calculate the intima-media thickness on the basis of the maximum value and the minimum value.
The major challenges which can be affected in finding the IMT are: (a) how well the ultrasound probe is gripped with the neck of a patient to scan the carotids; (b) how well the ultrasound gel is being applied; (c) the orientation of the probe; (d) demographics of the patient; (e) presence of calcium in the proximal walls; (f) skills of the sonographer or vascular surgeon; and (g) the threshold chosen for finding the peaks corresponding to the lumen-intima (LI) border points, and the media-adventitia (MA) border points (collectively denoted herein as the LIMA or LIMA points) for each signal orthogonal to the lumen. These challenges have complicated IMT measurement using conventional systems.
Thus, a computer-implemented system and method for fast, reliable and automated processing for intima-media thickness (IMT) measurements is needed.